DS200SHVIG1B is an SCR High Voltage Interface Board and is part of the GE Excitation EX2000 gas turbine control system. The SCR Voltage interface ( SHVI & SHVM ) boards provide attenuation for the bridge 3-phase AC voltage and DC bridge voltage and isolation for the field current shunt signals. These signals are cabled to the (DCFB) for use in metering and regulator control circuits therefore if an (SHVI) is present the shunt isolator on the (SHVI) is used and the shunt isolator on the (DCFB) is passed (SHVM) is a smaller version of (SHVI) card and is used on application with lower voltage DC field ratings.